%\usepackage{tikz}
%\usetikzlibrary{trees}

%\pagestyle{empty}

\begin{figure}
% Set the overall layout of the tree
\tikzstyle{level 1}=[level distance=3.5cm, sibling distance=3.5cm]
\tikzstyle{level 2}=[level distance=3.5cm, sibling distance=2cm]

% Define styles for bags and leafs
\tikzstyle{bag} = [text width=4em, text centered]
\tikzstyle{end} = [circle,minimum width=3pt,fill, inner sep=0pt]

% The sloped option gives rotated edge labels. Personally
% I find sloped labels a bit difficult to read. Remove the sloped options
% to get horizontal labels. 
\begin{tikzpicture}[grow=right]
\node[bag] {$ $}
    child {
        node[bag] {$A_i=(A,\cdot,\cdot)$\\ $p(A_i)$}        
            child {
                node[end, label=right:
                    {$C_j \rightarrow p(C_j)=p(A_{i}\cap \mathbf{R}_k)=p(\mathbf{R}_k|A)p(A)$}] {}
                edge from parent
                node[above] {$R_k$}
                node[below]  {$p(\mathbf{R}_k|A)$}
            }
            child {
                node[end, label=right:
                    {$ $}] {}
                edge from parent
                node[above] {$ $}
                node[below]  {$ $}
            }
            edge from parent 
            node[above] {$ $}
            node[below]  {$ $}
    }
    child {
        node[bag] {$ $}        
        child {
                node[end, label=right:
                    {$ $}] {}
                edge from parent
                node[above] {$ $}
                node[below]  {$ $}
            }
            child {
                node[end, label=right:
                    {$  $}] {}
                edge from parent
                node[above] {$ $}
                node[below]  {$ $}
            }
        edge from parent         
            node[above] {$ $}
            node[below]  {$ $}
    };
\end{tikzpicture}
\label{diag:tree_geral}
\caption{Arvore a retirada de duas bolas de uma urna com reposi\c{c}\~{a}o contendo 2 bolas vermelhas e 1 bola preta $C_j=(A_i,R_k,\cdot)=
A\cap \mathbf{R}_k$ e $\mathbf{R}_k=(\cdot,R_k,\cdot)$.}
\end{figure}